Labels to be attached to bottles for drinks (e.g. bottle for beer) are required to have a high adhesion strength to an article (e.g. bottle) and, after having been attached to an article (e.g. bottle), are required to have high water resistance when immersed in water and a property that they are peeled from the article in a short time when washed with an aqueous alkali solution (the property is hereinafter referred to as "alkali peelability").
As the adhesives used in such labels, there have been used starch-based adhesives, casein-based adhesives, polyvinyl alcohol-based adhesives, etc.; that is, "cold glues", etc.
In attaching a label to an article using a cold glue, a method is ordinarily adopted in which an adhesive is coated on the back side of a label and immediately the label is attached to an article. Therefore, in order to conduct this attaching operation continuously at a high speed, it is necessary to conduct two kinds of operations, namely, coating of an adhesive and attaching of a label mechanically. A machine having such functions is expensive and has been used only in limited fields.
Cold glues have had another problem. That is, cold glues ordinarily contain a slight amount of water for viscosity adjustment; when a cold glue is applied to a paper label and the label is attached to an article, the water in cold glue infiltrates into the label, inviting the curling (warpage) of the label.
Meanwhile, it was investigated to use, in applications where alkali peelability of a label is required, a pressure-sensitive adhesive having higher alkali solubility or swellability, obtained by slightly modifying the structure of the acrylic acid ester copolymer widely used as a conventional pressure-sensitive adhesive. In pressure-sensitive adhesives of acrylic acid ester copolymer type, however, the alkali peelability is insufficient in many cases; increase in alkali peelability results in reduced water resistance; when a beer bottle or the like to which a label using such a pressure-sensitive adhesive has been attached, is placed in water, the label tends to peel off.
The present invention is intended to provide a process for producing an article with a label satisfying that the label is attached to the article as an adhered with an adhesive layer having excellent resistance to ordinary water (e.g. tap water) and the label is easily peeled from the adhered by washing with an aqueous alkali solution.